Pre-Existing Health Conditions and Severe COVID-19 Outcomes: Umbrella Review and Meta-Analysis of Global Evidence

Background: This umbrella review summarises the global evidence on the risk of severe COVID-19 outcomes in patients with pre-existing health conditions. Methods: Systematic reviews (SRs) were identified in PubMed, Embase/Medline, and seven pre-print servers until December 11, 2020. Risk estimates (odds ratio (OR), hazard ratio (HR), relative risk (RR)) for hospitalisation, intensive care unit admission, intubation, and death were extracted from primary studies. Meta-analyses were performed stratified by regions of the World Health Organisation. The evidence certainty was assessed using GRADE. Registration number CRD42020215846. Findings: 160 primary studies from 120 SRs contributed 464 estimates for 42 pre-existing conditions. Most studies were conducted in North America, European, and Western Pacific regions.  Evidence from Africa, South/Latin America, and Eastern Mediterranean region was scarce. No evidence was available from South-East Asia region. Diabetes (HR 1∙2-2∙0 (1∙1-2∙8)), obesity (OR 1∙5-1∙75 (1∙1-2∙3)), heart failure (HR 1∙3-3∙3(0∙9-8∙2)), COPD (HR 1∙12-2∙2 (1∙1-3∙2)), and dementia (HR 1∙4-7.7 (1∙2-39∙6)) were associated with fatal COVID-19 in different regions, although the estimates varied. Evidence from Europe and North America showed that liver cirrhosis (OR 3∙2-5∙9 (0∙9-27∙7)) and active cancer (OR 1∙6-4∙7 (0∙5-14∙9)) were also associated with increased risk of death. Association between HIV and severe COVID-19 showed regional heterogeneity, with an increased risk of death in Africa (HR 1∙7 (1∙3-2∙2)). GRADE certainty was moderate to high for most associations. Interpretation: Risk of severe COVID-19 is consistently increased in certain patient subgroups across geographical regions, showing high variability in others. The results can be used to inform COVID-19 vaccine prioritisation or other intervention strategies. Funding Statement: Project ImVaCov – German Federal Ministry of Health Declaration of Interests: Authors declare no conflicts of interest.